Cut the potatoes in slices about the thickness of a pound coin (or thinner if cooking two smaller fish). Rub with the remaining 2 tablespoons oil, push half the remaining dill into the slits and season inside and out. Place on the bed of potatoes and put remaining dill into the belly. Step 3About 5 minutes before the fish will be ready, steam the baby leeks until tender - about 4 minutes. Step 4Move the fish and potatoes carefully to a heated platter, surround with the leeks and serve immediately.